The unidentified man, known only as Siavash, played a 15-year-old schoolboy for six weeks at Stoke HS in Ipswich, England.

Perceptive students seemed to immediately sense something was amiss when they noticed the 6-foot, 1-inch man sitting beside them.

“How’s there a 30-year-old man in our maths class?” a teen student wrote alongside a picture of the new classmate he posted to Snapchat.

Other students soon began sharing images seemingly pulled from the man’s Facebook account, showing him with the kind of facial hair few teenage boys could manage, a hairy chest and taking swigs from a beer.